1. Field of the Invention
The field of the invention lies in the area of effectively damped coiled springs, and, more particularly, in the area of mechanically effectively damped helically-wound coiled springs.
2. Description of the Prior Art
Perhaps the closest prior art device is shown and described in British Pat. No. 270,169 issued on May 5, 1927 to Timmis. The device described in this patent purportedly relates to improvements in coiled springs consisting of:
". . . springs of helical form, made from composite rods or bars, whose components are arranged concentrically, such rods or bars when coiled into the form of helical springs having in use a more uniform distribution of torsional stress, and at the same time providing an inherent dampening effect to the vibrations of the spring." (Page 1, Col. 1, Lines 9-16, inclusive). PA0 ". . . I arrange such rods or bars of any suitable material, and shaped so that the outer component embraces concentrically one or more components. To give an example, the outer component may be a tube of circular, elliptical or other section. The inner component or components may be of steel or other material preferably of a metallic nature. The outer component of tubular form, embraces another tube or solid bar; this inner component if of tubular construction, may also embrace a tube or solid bar, and so on. Such components may be touching one another throughout their length, or separated in any suitable manner. Each component forming this composite rod or bar, will, when coiled into a spring of helical shape, have in use a different period of free vibration to the other components; this will introduce a dampening action to the vibrations of the completed spring." (Page 1, Col. 1, Lines 17-22, inclusive, and Col. 2, Lines 23-40, inclusive.).
In this particular method of coiled spring construction, the composite spring which is described in this particular patent, does not actually provide for damping of the primary, or solid, spring, but instead assumes a period of vibration which is a mathematically predictable composite of the inherent, natural, free period of vibration of the two springs. Such composite frequency or period of vibration is clearly created via this construction because the ends of the two, or more, springs are contiguous so that when a dynamic force is impressed upon the composite spring, the end turns of the springs are contemporanously compressed or expanded depending on the nature of the applied force. Consequently, the motion of the composite spring cannot be described as being damped because the composite spring acts and functions as a single, new spring with an inherently different period of vibration than that of the other two, or more, springs from which the composite is constructed because the impressed force acts upon both simultaneously. Since this is the case, the highly desirable damping action does not occur as proposed and suggested by the patent.
True or actual coiled spring damping action is highly desirable for a number of reasons. One reason is that such damping would virtually eliminate the need for motion damping devices which are typically used in conjunction with springs, such as automobile shock absorbers. Another reason that such damping devices are desirable is that in the event that such springs would be used to isolate large buildings/equipments from vertical movements and rocking movements associated with horizontal movements, such vertical and horizontal displacements and/or movements would not be directly translated to the building structure but would be damped, that is, the springs'natural tendency to "track" or to "follow" the movement impressed on the support to the weight supported at the opposite end of the spring would be significantiy delayed in time and reduced in magnitude thereby resulting in substantially reduced destructive action upon the building/equipment structure. Presently, there is no effective mechanism for accomplishing these highly desired, and long sought-after spring damping features and/or characteristics.